The science teachers at New Hampshire’s Concord High School are no longer satisfied with what Wiggins and McTighe call the “teach, test, and hope for the best” learning cycle (2005). These teachers have been stepping up to the professional responsibility that demands more of them and their students—the responsibility to teach for understanding by continuously checking for understanding. This article chronicles some of the experiences of this dedicated group of teachers as they have worked together to build a collective understanding about teaching and learning.